A synchronous reluctance type rotary electric machine includes a rotor and a stator. The rotor includes a shaft rotatably supported and extending in an axial direction at a center of the rotating shaft, and a rotor core externally fitted and fixed to the shaft. The stator includes a stator core having a plurality of teeth disposed on an outer circumference of the rotor core to be spaced apart from the rotor core and disposed to be spaced apart from each other in a circumferential direction, and multipole multiphase armature windings respectively wound around the plurality of teeth.
Multi-layered hollow parts having a convex shape toward a side radially inward are formed for each pole in the rotor core. When the hollow parts are formed in this manner, a direction in which magnetic flux easily flows and a direction in which magnetic flux does not easily flow are formed in the rotor core. Thus, the synchronous reluctance type rotary electric machine rotates the shaft using a reluctance torque generated by the hollow parts.
Incidentally, it is conceivable that synchronous reluctance type rotary electric machines be applied in various fields, and thus yet higher output and reduction in size are required. Due to this, synchronous reluctance type rotary electric machines are desired to have a higher capacity and a higher rotation speed. On the other hand, when hollow parts are formed in a rotor core, the rotor core is likely to be deformed. Therefore, when the rotor core is rotated at a high-speed, there is a likelihood that the rotor core will be deformed by a centrifugal force generated by the high-speed rotation.
Here, when a thickness at a portion called a bridge formed between both ends in a longitudinal direction of the hollow part and an outer circumferential surface of the rotor core is set to be thick, a rotor core can be made difficult to deform. However, when a thickness of the bridge is set to be thick, there is a likelihood of generating magnetic flux leakage at the bridge portion (magnetic circuit). For this reason, a desired reluctance torque is not easily obtained, and there is a likelihood that torque characteristics of the synchronous reluctance type rotary electric machine will deteriorate.